Packet communication networks are experiencing greater and greater use. In addition, packet communication systems are being used for more and more wireless communications, such as in cellular phone systems, wherein audio and non-audio packet data may be transmitted over a combination of wired and wireless communication links.
Communication networks may include transcoders that modify packets passing through the network, such as by performing compression and de-compression on the packets, for example. The transcoding may be performed in order to reduce the amount of data to be transferred.
The transcoding may undesirably affect the packets. For example, the transcoding may be performed on audio data, such as VOIP packets. Wide Band (WB) High-Definition (HD) voice compression/decompression (i.e., codec) algorithms often require more kilobits-per-second (kbps) throughput than Narrow Band (NB) voice packets. The throughput required of WB codecs can comprise an undesirable and wasteful consumption of spectrum on a 3G or 4G Radio Access Network (RAN) if the end-to-end voice media path uses Narrow Band (NB) transcoding anywhere in the path. The WB codecs are wasteful if the packets are transcoded to NB because there is little or no perceptual benefit to the audio experience.
Unfortunately, because SIP may be used to initiate a HD voice call setup, and because of the hop-by-hop nature of SIP voice call signaling through a switched network using transcoding media gateways, it may be impossible to identify beforehand that transcoding will occur in a given call's media path.
One drawback of transcoding is that no indication of transcoding may be given to either the origination point or the destination point of a packet communication session. The origination point and the destination point may not know the level or severity of transcoding that has been performed on the communication session. Consequently, the origination point will not be able to initiate a communication session according to an expected transcoding.
Another drawback is that multiple transcoding processes may be performed on packets as they are transferred between points. Consequently, the origination point will not be able to configure the transmission of packets according to a narrowest expected transcoding.